Anatomy Unit 4: Cell Theory & Cellular Structures

Cell Theory Term “cell” was coined in 1665 by Robert Hooke when he looked at a slice of dried cork. He also observed that: 1. All living things are comprised of cells. 2. Cells are the smallest “living” unit in an organisms. 3. Cells come from previously existing cells. 4. Each cell maintains homeostasis

Cell Diversity Lots of shapes and sizes

Typical Cell

Cell Organization

The cell includes two basic parts: 1. Cell Membrane (outer covering of cell) 2. Cytoplasm Cytosol (fluid portion of the cytoplasm) Organelles (cell “organs” or functional parts)

Cell Organization

Cell Membrane Outer boundary Physical Chemical Comprised of two layers of lipid (fat) Outer and inner layers Proteins Proteins give the cell its unique “personality” or function

Cell Membrane

Membrane lipids The phospholipids in a cell membrane lie in two distinct layers. Hydrophobic tails on the inside of cell Hydrophilic heads on the outside of cell

Function of Membrane Proteins 1. Transport Channels (in and out of cell) 2. Receptors 3. Cell adhesion 4. Cell recognition

Membrane carbohydrates Functions: Lubrication Adhesion Cellular communication

Cell Illustrations Begin Cell Illustrations Phospholipid bilayer Cholesterol Proteins Lipids carbohydrates

Membrane Transport Permeability Impermeable Freely permeable Selectively permeable Passive processes Diffusion, osmosis Filtration Facilitated diffusion Active Processes active transport vesicular transport (endo- and exocytosis)

Diffusion Going from an area of higher concentration ( many collisions) to lower concentration (fewer collisions). Concentration gradient “Downhill” concentration gradient Equilibrium does not mean that diffusion stops, only that transport occurs at equal rates

Passive Transport Simple diffusion Facilitated diffusion Osmosis

Osmosis and Osmotic pressure Hypertonic Hypotonic Isotonic the water diffuses out of the cell, causing the cell to shrivel. the water diffuses into the cell, causing the cell to swell and possibly explode. the water diffuses into and out of the cell at the same rate.

Active Transport Active transport occurs when cells move materials against their concentration gradient, from an area of lower concentration to an area of higher concentration. Active transport requires a cell to expend or use energy.

Active Transport

Endocytosis Requires active transport. There are three types of endocytosis: Pinocytosis-the transport of solutes or fluids. Phagocytosis-the transport of large particles, whole cells, or solids. Receptor mediated endocytosis

Sodium Potassium Pump

Cellular Illustrations Please demonstrate active and passive transports on your cells

Cytoplasm Is comprised of: 1. Cytosol (fluid portion of the cytoplasm) 2. Organelles (cell “organs” or functional parts)

Cytosol Intracellular fluid Contains dissolved nutrients, ions, proteins and waste products

Cytoskeleton Internal protein framework of various threadlike filaments and hollow tubes Gives cytoplasm strength and flexibility Composed of Microfilaments Intermediate filaments Microtubules

Microfilaments Composed of actin Attached to the cell membrane by forming attachments with proteins in the membrane

Intermediate filaments Intermediate in size Strengthen cell and stabilize its position

Microtubules Hollow tubes built from the protein tubulin Gives cell strength and rigidity Anchors most organelles

Microvilli Finger like projections of the cell membrane Core supported by microfilaments (connects to cytoskeleton) Increase surface area of the membrane

Centrioles Cylindrical structure composed of microtubules Aid in cell mitosis Microtubules in triplets Each cell has one pair of centrioles

Nucleus

Control center of cell Contains DNA/chromosomes Genetic repository for ~ 35,000 genes Genes control the synthesis of proteins in each cell. Red blood cells don’t have a nucleus. Skeletal muscle cells have multiple nuclei.

Nuclear Envelope Double membrane Seperates nucleoplasm from cytosol Filled with nucleoplasm Covered in nuclear pores

Nucleolus Center of the nucleus Synthesize ribosomal RNA (rRNA) Most prominent in cells that manufacture large amounts of proteins

Endoplasmic reticulum (ER) A network of membrane-bound tunnels throughout the cytoplasm Connected to the nuclear envelope 2 types: Smooth and Rough

ER Rough ER Smooth ER

Ribosomes Particles attached to ER are ribosomes. Ribosomes are the site of protein synthesis within every cell.

Ribosomes

Proteasomnes Hollow cylindrical organelle Contain proteases Remove/recycle damaged or denatured proteans Break down abnormal proteins

Golgi Apparatus Flattened membranes Involved in packaging and secretion of proteins

Golgi Apparatus

Mitochondria Bean shaped Outer and inner membranes

Mitochondria Inner membrane folded into cristae Adenosine triphosphate (ATP) produced on cristae. ATP is high energy compound. ATP only produced in mitochondria.